CN107748111A - A kind of determination method of rock mass discontinuity Long-term Shear Strength - Google Patents
A kind of determination method of rock mass discontinuity Long-term Shear Strength Download PDFInfo
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- CN107748111A CN107748111A CN201710952723.5A CN201710952723A CN107748111A CN 107748111 A CN107748111 A CN 107748111A CN 201710952723 A CN201710952723 A CN 201710952723A CN 107748111 A CN107748111 A CN 107748111A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
- G01N2001/2873—Cutting or cleaving
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0025—Shearing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0071—Creep
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/0202—Control of the test
- G01N2203/0212—Theories, calculations
- G01N2203/0218—Calculations based on experimental data
Abstract
The invention discloses a kind of determination method of rock mass discontinuity Long-term Shear Strength.Rock mass discontinuity sample is prepared first；Shear creep laboratory test is carried out to sample, obtains the shear creep curve of sample；The Long-term Shear Strength section of rock mass discontinuity is determined by shear creep laboratory test；According to the shear creep curve of gained rock mass discontinuity sample, the shear creep model of sample is established, draws model parameter；According to specimen size and structure region feature, the numerical model of sample is established；Gained Long-term Shear Strength section is divided into several pieces, as the horizontal shearing stress value for intending applying in numerical experimentation, shear creep numerical experimentation is carried out to rock mass discontinuity sample, the exact value of rock mass discontinuity Long-term Shear Strength is obtained by shear creep numerical experimentation.The present invention is first depending on laboratory test results, determines the interval range of rock mass discontinuity Long-term Shear Strength, is then based on computational results, accurately draws the Long-term Shear Strength of rock mass discontinuity.
Description
First, technical field：
The present invention relates to rock mechanics and engineering field, and in particular to a kind of determination of rock mass discontinuity Long-term Shear Strength
Method.
2nd, background technology：
In water conservancy, mining, traffic, the energy and defence engineering, the various rock mass structures such as extensive development joint, weak intercalated layer
Face.The Long-term Shear Strength of rock mass discontinuity plays vital influence to the steady in a long-term of engineering and safety.Largely
Engineering practice shows, rockmass high slope, buried underground power house and overlength hydraulic tunnel are from starting to be deformed to final unstable failure
One complex nonlinear progression process relevant with the time, the deformation failure of the Long-term Shear Strength of rock mass discontinuity for engineering
The control action of key is served with unstability.When the shear stress of application is less than the Long-term Shear Strength of rock mass discontinuity, rock mass
The creep rate of structural plane is gradually reduced with the time, and rock mass discontinuity will not occur to destroy unstability；When the shear stress of application is higher than
During the Long-term Shear Strength of rock mass discontinuity, the creep rate of rock mass discontinuity is continuously increased with the time, and ultimately results in rock mass
Structural plane occurs to destroy unstability.Therefore, the research of rock mass discontinuity Long-term Shear Strength is for the steady in a long-term and safe of engineering
Evaluation has highly important theory and practice meaning.
At present, it is general to determine rock mass using the methods of tautochrone method, andrade creep method, the first bathmometry of creep curve
The Long-term Shear Strength of structural plane.These methods need to handle creep test curve, then according to obtained corresponding song
Line flex point determines the Long-term Shear Strength of rock mass discontinuity.However, the rock mass discontinuity Long-term Shear Strength that these methods obtain
Precision is not generally high.This is due to the position that artificial subjective visual inspection knee of curve is needed in Long-term Shear Strength determination process, by
This obtained rock mass discontinuity Long-term Shear Strength has random and inaccuracy；On the other hand, if rock mass discontinuity
During shear creep feature unobvious, obtained knee of curve unobvious are handled, cause to be difficult to directly estimate flex point from curve, from
And it can not accurately draw the Long-term Shear Strength of rock mass discontinuity.It is therefore proposed that one kind can overcome disadvantages mentioned above, the scope of application
Extensively, the high rock mass discontinuity Long-term Shear Strength of precision determines that method is very important.
3rd, the content of the invention：
The technical problem to be solved in the present invention is：In order to overcome existing rock mass discontinuity Long-term Shear Strength to determine in method
Existing weak point, the present invention provide a kind of determination method of rock mass discontinuity Long-term Shear Strength, and the inventive method can
Solve the problems, such as that the influence of prior art evaluation method human factor is big, precision is low；The long-term of rock mass discontinuity can accurately be drawn
Shearing strength.
In order to solve the above problems, the technical scheme that the present invention takes is：
The present invention provides a kind of determination method of rock mass discontinuity Long-term Shear Strength, and the determination method includes following step
Suddenly：
A, rock mass discontinuity sample is prepared；
B, shear creep laboratory test is carried out to the rock mass discontinuity sample of preparation, obtains the shear creep curve of sample；
C, the Long-term Shear Strength section of rock mass discontinuity is determined by shear creep laboratory test；
D, according to the shear creep curve of obtained rock mass discontinuity sample, the shear creep model of sample is established, is drawn
Model parameter；
E, according to the step a rock mass discontinuity specimen sizes prepared and structure region feature, sample is established in numerical software
Numerical model；
F, the Long-term Shear Strength section that step c is obtained is divided into several pieces, as the water for intending applying in numerical experimentation
Straight snips stress value, shear creep numerical experimentation is carried out to rock mass discontinuity sample, rock mass is obtained by shear creep numerical experimentation
The exact value of structural plane Long-term Shear Strength.
According to the determination method of above-mentioned rock mass discontinuity Long-term Shear Strength, the system of rock mass discontinuity sample in step a
Preparation Method is：
Sillar of the collection in worksite containing structural plane first, structural plane are the straight hard structural plane without filling；Using stone sawing machine
The sillar of collection is cut into regular block, regular block is cast into cuboid sample, structural plane with cement mortar after cutting
Positioned at the center position (to carry out shear creep laboratory test along structural plane position) of cuboid sample, that is, obtain rock mass structure
Interview sample.
According to the determination method of above-mentioned rock mass discontinuity Long-term Shear Strength, shear creep laboratory test in step b
Operating method is：
Conventional magnetic shear experiment is carried out to rock mass discontinuity sample first, draws the conventional shearing strength τ of rock mass discontinuityc；
Then shear creep laboratory test is carried out to rock mass discontinuity sample；Vertical stress according to suffered by rock mass discontinuity in engineering is big
It is small to determine experiment normal stress σ, apply normal stress σ to rock mass discontinuity sample to predetermined value, keep normal stress σ constant；
Apply the horizontal shearing stress τ of different stage to rock mass discontinuity sample from low to high using load mode respectively；The level is cut
Stress τ values determine according to rock mass discontinuity routine shear strength test result；By rock mass discontinuity routine shearing strength τc's
10%~15% as the horizontal shearing stress difference for intending applying in shear creep test, i.e. first order horizontal shearing stress is rock mass knot
Structure face routine shearing strength τc10%~15%, second level horizontal shearing stress is rock mass discontinuity routine shearing strength τc's
20%~30%, the rest may be inferred；After every grade of shear stress τ applies, keep shear stress τ invariable, observe and interrecord structure face
Shearing strain μ with time t changing rule；When shearing strain μ advances the speed less than 0.001mm/h, stop applying this grade of shear stress,
Apply next stage shear stress, untill creep rupture occurs for sample structure face, obtain the shear creep of rock mass discontinuity sample
Curve.
According to the determination method of above-mentioned rock mass discontinuity Long-term Shear Strength, the long-term shearing resistance of rock mass discontinuity in step c
The determination method of intensity interval is：
The shear creep curve for the rock mass discontinuity that step b is obtained is divided into three phases：Weakening creeping, steady state creep and add
The fast creep stage；In certain one-level shear stress τnIn the presence of, only there is weakening creeping and steady in rock mass discontinuity shear creep curve
The state creep stage, and in next stage shear stress τn+1In the presence of, rock mass discontinuity shear creep curve is by weakening creeping and surely
After the state creep stage, then there is the tertiary creep stage, cause rock mass discontinuity that shear creep occurs and destroy, then rock mass structure
The interval range of face Long-term Shear Strength is：τn~τn+1。
According to the determination method of above-mentioned rock mass discontinuity Long-term Shear Strength, rock mass discontinuity shearing is established in step d
Creep model, the operating method for drawing model parameter are：
According to the shear creep curve of obtained rock mass discontinuity sample, the shear creep characteristic in analytical structure face；Consider
Different creep phase characteristics, establish the mechanical model in rock mass discontinuity corresponding creep stage；When sample under axial stresses at different levels
Creep curve shows as weakening creeping and state creep stage, then from Xiyuan Model；Sample under what current axial stress
Creep curve show as weakening creeping and state creep stage, and under afterbody axial stress sample creep curve performance
For weakening creeping, steady state creep and tertiary creep stage, then from Rheological Model；It is compacted according to the rock mass discontinuity of foundation
Varying model, test data is recognized using least square method, regression analysis or particle swarm optimization algorithm；By constantly adjusting
Mould preparation shape parameter, models fitting curve is set to be overlapped as far as possible with trial curve, error of fitting obtains fitting in setting range
Creep model parameter of the optimized parameter as rock mass discontinuity.
The Creep Equation of Xiyuan Model is：
The Creep Equation of Rheological Model is：
In formula：τ is shear stress, and u is shearing strain, G1For instantaneous modulus of shearing, G2For viscoelasticity modulus of shearing, η1、η2、η3For
Coefficient of viscosity, τf、τsFor shear stress threshold value, a, b are creep parameters, and t is test period.
According to the determination method of above-mentioned rock mass discontinuity Long-term Shear Strength, rock mass discontinuity sample numerical value in step e
The method for building up of model is：
The test routine shearing strength drawn according to the step a rock mass discontinuity specimen sizes prepared and step b, in numerical value
Corresponding numerical model is established in software, and carries out mesh generation and cell assignment；The boundary condition of numerical model and experiment
Method is the same as step b；The obtained creep models of step d and model parameter are applied in numerical model, enable the numerical model
It is accurate to carry out rock mass discontinuity shear creep numerical experimentation.
According to the determination method of above-mentioned rock mass discontinuity Long-term Shear Strength, rock mass discontinuity sample is obtained in step f
The specific method of Long-term Shear Strength exact value is：
The rock mass discontinuity Long-term Shear Strength section that step c is obtained is divided into L parts, applied as plan in numerical experimentation
Horizontal shearing stress value, i.e. τn、…、τk、τk+1、…、τn+1, L values are true according to the rock mass discontinuity Long-term Shear Strength precision of setting
It is fixed；The Long-term Shear Strength precision of setting is higher, and L values are then bigger；The numerical model that applying step e is established, using loading respectively
Mode applies horizontal shearing stress from low to high, carries out rock mass discontinuity shear creep numerical experimentation, draws and tied under every grade of shear stress
The shearing strain μ in structure face with time t change curve；When in kth level shear stress τkUnder effect, the shear creep number of rock mass discontinuity
Value trial curve shows as weakening creeping and state creep stage, and in+1 grade of shear stress τ of kthk+1Under effect, rock mass discontinuity
Shear creep numerical experimentation curve after weakening creeping and state creep stage, there is tertiary creep stage, rock mass knot
Structure face occurs shear creep and destroyed, then shear stress τkFor the exact value of the Long-term Shear Strength of rock mass discontinuity.
The present invention is first depending on laboratory test results, determines the interval range of rock mass discontinuity Long-term Shear Strength, then
Based on computational results, the Long-term Shear Strength of rock mass discontinuity is accurately drawn.
The positive beneficial effect of the present invention：
1st, existing rock mass discontinuity Long-term Shear Strength determines method at present, uncontrollable to solve obtained long-term shearing resistance
Intensity accuracy；The present invention can preset Long-term Shear Strength precision to be solved, can accurately draw rock mass discontinuity
Long-term Shear Strength, the shortcomings that conventional method subjectivity differentiates, error is big is overcome, makes result of calculation more objective, more scientific, is rock
The determination of body structural plane Long-term Shear Strength provides a kind of controllable new method of precision.
2nd, rock mass discontinuity shear creep laboratory test cost is big, cycle length, and the shear stress series that can apply is few, can not
The prerupture magnitude of maximum shearing stress of rock mass discontinuity shear creep, i.e. Long-term Shear Strength are immediately arrived at, is only capable of drawing rock mass knot
The section of structure face Long-term Shear Strength；Rock mass laboratory test and numerical experimentation are combined by the present invention, will according to the precision of setting
The Long-term Shear Strength section that laboratory test is drawn is divided into several pieces value of shearing, using expense is low, precision is high, can weigh repeatedly
Multiple numerical experimentation, the irrealizable a large amount of multistage shear stress loadings of exact reproduction laboratory test institute, from Long-term Shear Strength area
Between in immediately arrive at the prerupture magnitude of maximum shearing stress of rock mass discontinuity shear creep, can accurately draw the length of rock mass discontinuity
Phase shearing strength value.
3rd, the present invention has played the advantages of numerical experimentation, the shortcomings that compensate for laboratory test, it is easy to spread be applied to it is actual
In rock mass engineering project.
4th, illustrate：
The determination method flow schematic diagram of Fig. 1 rock mass discontinuity Long-term Shear Strengths of the present invention；
Fig. 2 sandstone structural plane shear creep laboratory test curves；
Fig. 3 rock mass discontinuity creep curve stage schematic diagrames；
Fig. 4 determines the exact value of sandstone structural plane Long-term Shear Strength based on numerical experimentation curve；
Fig. 5 griotte structural plane shear creep laboratory test curves；
Fig. 6 determines the exact value of griotte structural plane Long-term Shear Strength based on numerical experimentation curve.
5th, embodiment：
The present invention is expanded on further with reference to embodiments, but is not intended to limit the technology contents that the present invention protects.
The determination method operating process schematic diagram of rock mass discontinuity Long-term Shear Strength of the present invention is referred to shown in accompanying drawing 1.
Embodiment 1：
By taking Central China hydraulic engineering sandstone as an example, based on laboratory test and numerical experimentation, sandstone structural plane is determined
Long-term Shear Strength, concrete operation step are as follows：
A, sandstone sillar of the collection in worksite containing structural plane, structural plane are the straight hard structural plane without filling；Using saw stone
Machine-cut cuts sillar, and then cube structure that sillar is cast into 15cm × 15cm × 15cm with cement mortar interviews sample, structure
Face is located at the center position of cuboid sample；
B, first, conventional magnetic shear experiment is carried out to sandstone structural fece sample using rock shearing instrument, according to rock mass in engineering
Actual vertical stress size suffered by structural plane, normal stress σ are taken as 2.39MPa, and the conventional shearing resistance for obtaining sandstone structural plane is strong
Spend τcFor 2.86MPa；Then, shear creep laboratory test is carried out to sandstone structural fece sample using rheometer, with routine test
In normal stress σ values it is identical, in shear creep test to sandstone structural fece sample apply normal stress σ be also 2.39MPa,
Keep normal stress σ constant；Horizontal shearing stress τ is applied using load mode respectively, horizontal shearing stress τ is respectively sandstone structural plane
Test routine shearing strength τc15%, 30%, 45%, 60% and 75%, i.e. 0.43MPa, 0.86MPa, 1.29MPa,
1.72MPa and 2.15MPa；After every grade of shear stress τ applies, keep shear stress τ invariable, observe and record sandstone structural plane
Shearing strain μ with time t changing rule；When shearing strain μ advances the speed less than 0.001mm/h, stop applying this grade of shear stress,
Apply next stage shear stress, untill creep rupture occurs for sandstone structural plane, obtain the shear creep of sandstone structural fece sample
Curve (as shown in Figure 2)；
C, the shear creep curve for the sandstone structural plane that step b is obtained can be divided into three phases：Weakening creeping, stable state are compacted
Become and the tertiary creep stage (as shown in Figure 3)；Horizontal shearing stress τ be respectively 0.43MPa, 0.86MPa, 1.29MPa and
Under 1.72MPa effects, only there is weakening creeping and state creep stage in sandstone structural plane shear creep curve, and is cut in level
Stress τ is that weakening creeping, steady state creep and acceleration occurs respectively in sandstone structural plane shear creep curve under 2.15MPa effects
In the creep stage, shear creep, which occurs, for sandstone structural plane destroys, then the Long-term Shear Strength interval range of sandstone structural plane is：
1.72MPa~2.15MPa；
D, according to the shear creep curve of the obtained sandstone structural planes of step b, the shear creep characteristic in analytical structure face；Choosing
Weakening creeping, steady state creep and the tertiary creep stage of sandstone structural plane are described with Rheological Model；Using least square
Method recognizes to test data, the match value of setting model and the coefficient correlation square R of test value2More than 0.95, draw not
With the creep model parameter of sandstone structural plane under shear stress, as shown in table 1；
The creep model parameter of sandstone structural plane under 1 different shear stress of table
E, the structure obtained according to the step a rock mass discontinuity specimen size 15cm × 15cm × 15cm prepared and step b
Face shearing strength τc=2.86MPa, in finite difference software FLAC3DIn establish corresponding sandstone structural plane numerical model, go forward side by side
Row mesh generation and cell assignment；The Rheological Model that step d is obtained is subjected to secondary development and is embedded into FLAC3DSoftware
In, the model parameter that step d is obtained is applied in numerical model；Fixed boundary condition is applied to sample bottom, to sample top
Portion applies normal stress, and normal stress size is identical with step b laboratory tests, is also 2.39MPa, keeps normal stress constant not
Become；To sandstone structural plane apply setting shear stress, keep shear stress it is constant, software records and export sandstone structural plane cut should
Become change curves of the u with time t；Change the value of shearing applied, the numerical model is accurately carried out under different shear stress
The shear creep numerical experimentation of sandstone structural plane；
F, Long-term Shear Strength precision to be solved is set as 0.01MPa, then the sandstone structural plane obtained step c is long-term
Shearing strength section 1.72MPa~2.15MPa is divided into 43 parts, and the horizontal shearing stress for intending applying in numerical experimentation is respectively
1.73MPa、1.74MPa、1.75MPa、…、2.15MPa；The sandstone structural plane numerical model that applying step e is established, from low to high
Apply above-mentioned value of shearing step by step, carry out sandstone structural plane shear creep numerical experimentation；When shear stress increases to 1.97MPa,
Still only there is weakening creeping and state creep stage in the shear creep numerical experimentation curve of sandstone structural plane, does not accelerate
The creep stage, and under next stage shear stress 1.98MPa effects, the shear creep numerical experimentation curve of sandstone structural plane is by declining
Subtract creep and state creep stage, the tertiary creep stage (as shown in Figure 4) occur, then the precision according to setting, sandstone knot
The Long-term Shear Strength in structure face is 1.97MPa.
Embodiment 2：
By taking Southwestern China hydraulic engineering griotte as an example, based on laboratory test and numerical experimentation, griotte structure is determined
The Long-term Shear Strength in face, concrete operation step are as follows：
A, griotte sillar of the collection in worksite containing structural plane, structural plane are the straight hard structural plane without filling；Using saw
Stone machine-cut cuts sillar, and then cube structure that sillar is cast into 15cm × 15cm × 15cm with cement mortar interviews sample, knot
Structure face is located at the center position of cuboid sample；
B, first, conventional magnetic shear experiment is carried out to griotte structural fece sample using rock shearing instrument, according to rock in engineering
Actual vertical stress size suffered by body structural plane, normal stress σ are taken as 5.41MPa, and the routine for obtaining griotte structural plane resists
Cut intensity τcFor 6.10MPa；Then, shear creep laboratory test is carried out to griotte structural fece sample using rheometer, it is and normal
Normal stress σ values in rule experiment are identical, and the normal stress σ applied in shear creep test to griotte structural fece sample is also
5.41MPa, keep normal stress σ constant；Horizontal shearing stress τ is applied using load mode respectively, horizontal shearing stress τ is respectively big
Manage rock structural fece sample routine shearing strength τc10%, 20%, 30%, 40%, 50% and 60%, i.e. 0.61MPa,
1.22MPa, 1.83MPa, 2.44MPa, 3.05MPa and 3.66MPa；After every grade of shear stress τ applies, keep shear stress τ constant not
Become, observe and record the shearing strain μ of griotte structural plane with time t changing rule；It is less than when shearing strain μ advances the speed
During 0.001mm/h, stop applying this grade of shear stress, apply next stage shear stress, until creep rupture occurs for griotte structural plane
Untill, obtain the shear creep curve (as shown in Figure 5) of griotte structural fece sample；
C, the shear creep curve for the griotte structural plane that step b is obtained can be divided into three phases：Weakening creeping, stable state
Creep and tertiary creep stage；Horizontal shearing stress τ be respectively 0.61MPa, 1.22MPa, 1.83MPa, 2.44MPa and
Under 3.05MPa effects, only there is weakening creeping and state creep stage in griotte structural plane shear creep curve, and in level
Shear stress τ be 3.66MPa effect under, griotte structural plane shear creep curve occur respectively weakening creeping, steady state creep and
In the tertiary creep stage, shear creep, which occurs, for griotte structural plane destroys, then the Long-term Shear Strength section model of griotte structural plane
Enclosing is：3.05MPa~3.66MPa；
D, according to the shear creep curve of the obtained griotte structural planes of step b, the shear creep characteristic in analytical structure face；
Weakening creeping, steady state creep and the tertiary creep stage of griotte structural plane are described from Rheological Model；Using minimum
Square law recognizes to test data, the match value of setting model and the coefficient correlation square R of test value2More than 0.95, obtain
Go out the creep model parameter (as shown in table 2) of griotte structural plane under different shear stress；
The creep model parameter of griotte structural plane under 2 different shear stress of table
E, the structure obtained according to the step a rock mass discontinuity specimen size 15cm × 15cm × 15cm prepared and step b
Face shearing strength τc=6.10MPa, in finite difference software FLAC3DIn establish corresponding griotte structural plane numerical model, and
Carry out mesh generation and cell assignment；The Rheological Model that step d is obtained is subjected to secondary development and is embedded into FLAC3DIt is soft
In part, the model parameter that step d is obtained is applied in numerical model；Fixed boundary condition is applied to sample bottom, to sample
Top applies normal stress, and normal stress size is identical with step b laboratory tests, is also 5.41MPa, keeps normal stress constant
It is constant；Apply the shear stress of setting to griotte structural plane, holding shear stress is constant, and software records simultaneously export griotte structural plane
Shearing strain u with time t change curve；Change the value of shearing applied, the numerical model is accurately carried out difference and cut
The shear creep numerical experimentation of griotte structural plane under stress；
F, Long-term Shear Strength precision to be solved is set as 0.001MPa, then the griotte structural plane obtained step c
Long-term Shear Strength section 3.05MPa~3.66MPa is divided into 610 parts, intends the horizontal shearing stress difference applied in numerical experimentation
For 3.051MPa, 3.052MPa, 3.053MPa ..., 3.660MPa；The griotte structural plane numerical model that applying step e is established,
Apply above-mentioned value of shearing step by step from low to high, carry out griotte structural plane shear creep numerical experimentation；When shear stress increases to
During 3.397MPa, still only there is weakening creeping and steady state creep rank in the shear creep numerical experimentation curve of griotte structural plane
Section, there is not the tertiary creep stage, and under next stage shear stress 3.398MPa effects, the shear creep of griotte structural plane
Numerical experimentation curve passes through weakening creeping and state creep stage, the tertiary creep stage (as shown in Figure 6) occurs, then foundation
The precision of setting, the Long-term Shear Strength of griotte structural plane is 3.397MPa.
Claims (7)
- A kind of 1. determination method of rock mass discontinuity Long-term Shear Strength, it is characterised in that the determination method includes following step Suddenly：A, rock mass discontinuity sample is prepared；B, shear creep laboratory test is carried out to the rock mass discontinuity sample of preparation, obtains the shear creep curve of sample；C, the Long-term Shear Strength section of rock mass discontinuity is determined by shear creep laboratory test；D, according to the shear creep curve of obtained rock mass discontinuity sample, the shear creep model of sample is established, draws model Parameter；E, according to the step a rock mass discontinuity specimen sizes prepared and structure region feature, the number of sample is established in numerical software It is worth model；F, the Long-term Shear Strength section that step c is obtained is divided into several pieces, cut as the level for intending applying in numerical experimentation Stress value, shear creep numerical experimentation is carried out to rock mass discontinuity sample, rock mass structure is obtained by shear creep numerical experimentation The exact value of face Long-term Shear Strength.
- 2. the determination method of rock mass discontinuity Long-term Shear Strength according to claim 1, it is characterised in that in step a The preparation method of rock mass discontinuity sample is：Sillar of the collection in worksite containing structural plane first, structural plane are the straight hard structural plane without filling；It will be adopted using stone sawing machine The sillar of collection cuts into regular block, regular block is cast into cuboid sample with cement mortar after cutting, structural plane is located at The center position of cuboid sample, that is, obtain rock mass discontinuity sample.
- 3. the determination method of rock mass discontinuity Long-term Shear Strength according to claim 1, it is characterised in that in step b The operating method of shear creep laboratory test is：Conventional magnetic shear experiment is carried out to rock mass discontinuity sample first, draws the conventional shearing strength τ of rock mass discontinuityc；Then it is right Rock mass discontinuity sample carries out shear creep laboratory test；Vertical stress size according to suffered by rock mass discontinuity in engineering determines Normal stress σ is tested, applies normal stress σ to rock mass discontinuity sample to predetermined value, keeps normal stress σ constant；Using point Other load mode applies the horizontal shearing stress τ of different stage to rock mass discontinuity sample from low to high；The horizontal shearing stress τ values Determined according to rock mass discontinuity routine shear strength test result；By rock mass discontinuity routine shearing strength τc10%~15% As the horizontal shearing stress difference for intending applying in shear creep test, i.e. first order horizontal shearing stress is that rock mass discontinuity is routinely anti- Cut intensity τc10%~15%, second level horizontal shearing stress is rock mass discontinuity routine shearing strength τc20%~30%, according to This analogizes；After every grade of shear stress τ applies, keep shear stress τ invariable, observe and the shearing strain μ in interrecord structure face is with time t Changing rule；When shearing strain μ advances the speed less than 0.001mm/h, stop applying this grade of shear stress, application next stage is cut should Power, untill creep rupture occurs for sample structure face, obtain the shear creep curve of rock mass discontinuity sample.
- 4. the determination method of rock mass discontinuity Long-term Shear Strength according to claim 1, it is characterised in that in step c The determination method in rock mass discontinuity Long-term Shear Strength section is：The shear creep curve for the rock mass discontinuity that step b is obtained is divided into three phases：Weakening creeping, steady state creep and acceleration are compacted The change stage；In certain one-level shear stress τnIn the presence of, rock mass discontinuity shear creep curve weakening creeping only occurs and stable state is compacted The change stage, and in next stage shear stress τn+1In the presence of, rock mass discontinuity shear creep curve is compacted by weakening creeping and stable state After the change stage, then there is the tertiary creep stage, cause rock mass discontinuity that shear creep occurs and destroy, then rock mass discontinuity is grown The interval range of phase shearing strength is：τn~τn+1。
- 5. the determination method of rock mass discontinuity Long-term Shear Strength according to claim 1, it is characterised in that in step d The operating method for establish rock mass discontinuity shear creep model, drawing model parameter is：According to the shear creep curve of obtained rock mass discontinuity sample, the shear creep characteristic in analytical structure face；Consider different Creep phase characteristic, establish the mechanical model in rock mass discontinuity corresponding creep stage；When the creep of sample under axial stresses at different levels Curve shows as weakening creeping and state creep stage, then from Xiyuan Model；Sample is compacted under what current axial stress Varied curve shows as weakening creeping and state creep stage, and the creep curve of sample shows as declining under afterbody axial stress Subtract creep, steady state creep and tertiary creep stage, then from Rheological Model；According to the rock mass discontinuity creep mould of foundation Type, test data is recognized using least square method, regression analysis or particle swarm optimization algorithm；By constantly adjusting mould Shape parameter, models fitting curve is set to be overlapped as far as possible with trial curve, error of fitting obtains fitting most in setting range Creep model parameter of the excellent parameter as rock mass discontinuity.
- 6. the determination method of rock mass discontinuity Long-term Shear Strength according to claim 1, it is characterised in that in step e The method for building up of rock mass discontinuity sample numerical model is：The test routine shearing strength drawn according to the step a rock mass discontinuity specimen sizes prepared and step b, in numerical software In establish corresponding numerical model, and carry out mesh generation and cell assignment；The boundary condition and test method of numerical model With step b；The obtained creep models of step d and model parameter are applied in numerical model, enable the numerical model accurate Carry out rock mass discontinuity shear creep numerical experimentation.
- 7. the determination method of rock mass discontinuity Long-term Shear Strength according to claim 1, it is characterised in that in step f Obtain rock mass discontinuity sample Long-term Shear Strength exact value specific method be：The rock mass discontinuity Long-term Shear Strength section that step c is obtained is divided into L parts, as the water for intending applying in numerical experimentation Straight snips stress value, i.e. τn、…、τk、τk+1、…、τn+1, L values are according to the determination of the rock mass discontinuity Long-term Shear Strength precision of setting； The Long-term Shear Strength precision of setting is higher, and L values are then bigger；The numerical model that applying step e is established, using load mode respectively Apply horizontal shearing stress from low to high, carry out rock mass discontinuity shear creep numerical experimentation, draw structural plane under every grade of shear stress Shearing strain μ with time t change curve；When in kth level shear stress τkUnder effect, the shear creep numerical value examination of rock mass discontinuity Test curve and show as weakening creeping and state creep stage, and in+1 grade of shear stress τ of kthk+1Under effect, rock mass discontinuity is cut Creep numerical experimentation curve is cut after weakening creeping and state creep stage, tertiary creep stage, rock mass discontinuity occurs Generation shear creep destroys, then shear stress τkFor the exact value of the Long-term Shear Strength of rock mass discontinuity.
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